THz time domain spectroscopy of biomolecular conformational modes.

abstract：:The purpose of this study was the evaluation of the impact of a variable relative biological effectiveness (RBE) compared to a constant RBE value of 1.1 in proton therapy prostate trials due to uncertainties in α/β ratio. Twenty patients receiving passive scattered proton therapy (PSPT) and fifteen patients receiving ...

journal_title：Physics in medicine and biology

authors： Marteinsdottir M,Paganetti H

更新日期：2019-06-05 00:00:00

abstract：:A method for simulating spot-scanned delivery to a moving tumour was developed which uses patient-specific image and plan data. The magnitude of interplay effects was investigated for two patient cases under different fractionation and respiratory motion variation scenarios. The use of volumetric rescanning for motion...

journal_title：Physics in medicine and biology

authors： Kraus KM,Heath E,Oelfke U

更新日期：2011-10-21 00:00:00

abstract：:Four dimensional cone beam computed tomography (4DCBCT) uses a constant gantry speed and imaging frequency that are independent of the patient's breathing rate. Using a technique called respiratory motion guided 4DCBCT (RMG-4DCBCT), we have previously demonstrated that by varying the gantry speed and imaging frequency...

journal_title：Physics in medicine and biology

authors： O'Brien RT,Stankovic U,Sonke JJ,Keall PJ

更新日期：2017-06-07 00:00:00

abstract：:Time- and space-resolved diffuse reflectance measurements were used to identify the optical parameters, the reduced scattering and absorption coefficients, of bulk living tissue in the region from 1.15 to 1.52 microm. Although in this region the detector was limited in its temporal resolution, we applied a peak-time s...

journal_title：Physics in medicine and biology

authors： Nishimura G,Kida I,Tamura M

更新日期：2006-06-07 00:00:00

abstract：:To address the quality assurance (QA) of a MR-linac which is an MRI combined with a linear accelerator (linac), the traditional linac QA-tests need to be redesigned, since the presence of the static magnetic field in the MR-linac alters the electron trajectory. The latter causes the asymmetry in the dose kernel which ...

journal_title：Physics in medicine and biology

authors： van Zijp HM,van Asselen B,Wolthaus JW,Kok JM,de Vries JH,Ishakoglu K,Beld E,Lagendijk JJ,Raaymakers BW

更新日期：2016-02-07 00:00:00

abstract：:In medical imaging different techniques have been developed to gain information from inside a tissue. Optoacoustics is a method to generate tomography pictures of tissue using Q-switched laser pulses. Due to thermal and pressure confinement, a short light pulse generates a pressure distribution inside tissue, which mi...

journal_title：Physics in medicine and biology

authors： Köstli KP,Frenz M,Bebie H,Weber HP

更新日期：2001-07-01 00:00:00

abstract：:An open-ended coaxial probe is often used for investigating the dielectric properties of biological tissues. The present study indicates that in addition to the probe size, the penetration of the electromagnetic (EM) fields of an open-ended coaxial probe in contact with the skin is dependent on the applied frequency b...

journal_title：Physics in medicine and biology

authors： Alanen E,Lahtinen T,Nuutinen J

更新日期：1999-07-01 00:00:00

abstract：:The delivery of volumetric modulated arc therapy (VMAT) requires the simultaneous movement of the linear accelerator gantry, multi-leaf collimators and jaws while the dose rate is varied. In this study, a VMAT delivery emulator was developed to accurately predict the characteristics of a given treatment plan, incorpor...

journal_title：Physics in medicine and biology

authors： Boylan CJ,Rowbottom CG,Mackay RI

更新日期：2011-07-07 00:00:00

abstract：:The radiofrequency dielectric behaviour of packed human erythrocytes has been investigated in normal haemoglobins F and AA and also abnormal haemoglobins homozygous SS and heterozygous AS. Dielectric measurements were made in tightly packed blood cells at an average room temperature of 26.5 +/- 0.5 degrees C in the fr...

journal_title：Physics in medicine and biology

authors： Laogun AA,Ajayi NO,Okafor LO,Osamo NO

更新日期：1983-04-01 00:00:00

abstract：:Ultrasound may provide a quantitative technique for the characterization of cartilage changes typical of early osteoarthrosis. In this study, specific changes in bovine articular cartilage were induced using collagenase and chondroitinase ABC, enzymes that selectively degrade collagen fibril network and digest proteog...

journal_title：Physics in medicine and biology

authors： Töyräs J,Rieppo J,Nieminen MT,Helminen HJ,Jurvelin JS

更新日期：1999-11-01 00:00:00

abstract：:In this study, we evaluate the feasibility of designing a beveled fiber-optic probe coupled with a ball lens for improving depth-resolved fluorescence measurements of epithelial tissue using Monte Carlo (MC) simulations. The results show that by using the probe configuration with a beveled tip collection fiber and a f...

journal_title：Physics in medicine and biology

authors： Jaillon F,Zheng W,Huang Z

更新日期：2008-02-21 00:00:00

abstract：:Numerous studies have reported the measurements of the dielectric properties of the skin. Clarifying the manner in which the human body interacts with electromagnetic waves is essential for medical research and development, as well as for the safety assessment of electromagnetic wave exposure. The skin comprises sever...

journal_title：Physics in medicine and biology

authors： Sasaki K,Wake K,Watanabe S

更新日期：2014-08-21 00:00:00

abstract：:It has been reported that the dose effects of metallic guidewires are significant in intravascular brachytherapy (IVBT) using a beta source. The purpose of this work is to investigate the dependence of these dose effects on guidewire position. The EGS4 Monte Carlo codes were used to perform the dose calculations for t...

journal_title：Physics in medicine and biology

authors： Shih R,Hsu WL,Li XA

更新日期：2002-05-21 00:00:00

abstract：:A new component module (CM), designated DYNVMLC, was developed to fully model the geometry of the Varian Millennium 120 leaf collimator using the BEAMnrc Monte Carlo code. The model includes details such as the leaf driving screw hole, support railing groove and leaf tips. Further modifications also allow sampling of ...

journal_title：Physics in medicine and biology

authors： Heath E,Seuntjens J

更新日期：2003-12-21 00:00:00

abstract：:IMRT optimization is an iterative process in which many dose calculations may be necessary. A fast and accurate dose calculation engine is essential for the optimization program to converge to a reliable solution in a reasonable time. Previously we developed a fast dose calculation method for IMRT optimization based o...

journal_title：Physics in medicine and biology

authors： Wu Q

更新日期：2004-10-07 00:00:00

abstract：:Models of the electrical properties of biological tissue have been the subject of many studies. These models have sought to explain aspects of the dielectric dispersion of tissue. This paper develops a mathematical model of the complex permittivity of tissue as a function of frequency f, in the range 10(4) < f < 10(7)...

journal_title：Physics in medicine and biology

authors： Smye SW,Evans CJ,Robinson MP,Sleeman BD

更新日期：2007-12-07 00:00:00

abstract：:A hybrid differential and spatially resolved spectroscopy (SRS) technique has been developed to measure absolute absorption coefficient (mu(a)), reduced scattering coefficient (mu'(s)) and cerebral blood volume (CBV) in the adult human head. A spectrometer with both differential and SRS capabilities has been used to c...

journal_title：Physics in medicine and biology

authors： Leung TS,Tachtsidis I,Smith M,Delpy DT,Elwell CE

更新日期：2006-02-07 00:00:00

abstract：:Speed of sound (SOS) measurements, typically made using 1 MHz broadband pulses, are increasingly used in the clinical diagnosis of bone disorders. Previous in vitro studies indicate that broadband ultrasound pulses are susceptible to distortion in cancellous bone, leading to imprecise arrival time and SOS measurements...

journal_title：Physics in medicine and biology

authors： Pollintine P,Haddaway MJ,Davie MW

更新日期：2000-07-01 00:00:00

abstract：:In response to the recognized fragility of reactor-produced (99)Mo supply, direct production of (99m)Tc via (100)Mo(p,2n)(99m)Tc reaction using medical cyclotrons has been investigated. However, due to the existence of other Molybdenum (Mo) isotopes in the target, in parallel with (99m)Tc, other technetium (Tc) radioa...

journal_title：Physics in medicine and biology

authors： Hou X,Tanguay J,Buckley K,Schaffer P,Bénard F,Ruth TJ,Celler A

更新日期：2016-01-21 00:00:00

abstract：:Single monochromator charge-coupled device (CCD) array spectroradiometers have the advantage of ease of use and speed compared with double grating instruments. Their inherently inferior stray-light rejection, however, can critically affect their accuracy in phototherapy and research-related dosimetry applications. Thi...

journal_title：Physics in medicine and biology

authors： Coleman A,Sarkany R,Walker S

更新日期：2008-09-21 00:00:00

abstract：:Irradiation of moving targets using a scanned ion beam can cause clinically intolerable under- and overdosages within the target volume due to the interplay effect. Several motion mitigation techniques such as gating, beam tracking and rescanning are currently investigated to overcome this restriction. To enable detai...

journal_title：Physics in medicine and biology

authors： Steidl P,Richter D,Schuy C,Schubert E,Haberer T,Durante M,Bert C

更新日期：2012-04-21 00:00:00

abstract：:Recent studies of the minute morphology of the skin by optical coherence tomography revealed that the sweat ducts in human skin are helically shaped tubes, filled with a conductive aqueous solution. This, together with the fact that the dielectric permittivity of the dermis is higher than that of the epidermis, brings...

journal_title：Physics in medicine and biology

authors： Feldman Y,Puzenko A,Ben Ishai P,Caduff A,Davidovich I,Sakran F,Agranat AJ

更新日期：2009-06-07 00:00:00

abstract：:Poly(vinyl alcohol) cryogel, PVA-C, is presented as a tissue-mimicking material, suitable for application in magnetic resonance (MR) imaging and ultrasound imaging. A 10% by weight poly(vinyl alcohol) in water solution was used to form PVA-C, which is solidified through a freeze-thaw process. The number of freeze-thaw...

journal_title：Physics in medicine and biology

authors： Surry KJ,Austin HJ,Fenster A,Peters TM

更新日期：2004-12-21 00:00:00

abstract：:Numerous studies of early-stage breast cancer treated with breast conserving surgery (BCS) and radiotherapy (RT) have been published in recent years. Both external beam radiotherapy (EBRT) and/or brachytherapy (BT) with different fractionation schemes are currently used. The present RT practice is largely based on emp...

journal_title：Physics in medicine and biology

authors： Guerrero M,Li XA

更新日期：2003-10-21 00:00:00

abstract：:In this paper we present the results of a dosimetric evaluation of a 2D ionization chamber array with the objective of its implementation for quality assurance in clinical routine. The pixel ionization chamber MatriXX (Scanditronix Wellhofer, Germany) consists of 32x32 chambers with a distance of 7.6 mm between chambe...

journal_title：Physics in medicine and biology

authors： Herzen J,Todorovic M,Cremers F,Platz V,Albers D,Bartels A,Schmidt R

更新日期：2007-02-21 00:00:00

abstract：:The spatial resolution of 2D detector arrays equipped with ionization chambers or diodes, used for the dose verification of IMRT treatment plans, is limited by the size of the single detector and the centre-to-centre distance between the detectors. Optimization criteria with regard to these parameters have been develo...

journal_title：Physics in medicine and biology

authors： Poppe B,Djouguela A,Blechschmidt A,Willborn K,Rühmann A,Harder D

更新日期：2007-05-21 00:00:00

abstract：:IMRT delivery follows a planned leaf sequence, which is optimized before treatment delivery. However, it is hard to model real-time variations, such as respiration, in the planning procedure. In this paper, we propose a negative feedback system of IMRT delivery that incorporates real-time optimization to account for i...

journal_title：Physics in medicine and biology

authors： Lu W,Chen M,Ruchala KJ,Chen Q,Langen KM,Kupelian PA,Olivera GH

更新日期：2009-07-21 00:00:00

abstract：:Developments in positron emission tomography (PET) technology have resulted in systems with finer detector elements designed to further improve spatial resolution. However, there is a limit to what extent reducing detector element size will improve spatial resolution in PET. The spatial resolution of PET imaging is li...

journal_title：Physics in medicine and biology

authors： Levin CS,Hoffman EJ

更新日期：1999-03-01 00:00:00

abstract：:We report on a novel method for simultaneous biological optimization of treatment plans for hypoxic tumors using multiple ion species. Our previously introduced kill painting approach, where the overall cell killing is optimized on biologically heterogeneous targets, was expanded with the capability of handling differ...

journal_title：Physics in medicine and biology

authors： Sokol O,Krämer M,Hild S,Durante M,Scifoni E

更新日期：2019-02-08 00:00:00

abstract：:This study was carried out to investigate whether the electronic portal imaging (EPI) acquisition process could be optimized, and as a result tolerance and action levels be set for the PIPSPro QC-3V phantom image quality assessment. The aim of the optimization process was to reduce the dose delivered to the patient wh...

journal_title：Physics in medicine and biology

authors： McGarry CK,Grattan MW,Cosgrove VP

更新日期：2007-12-07 00:00:00